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High-energy ion treatments of amorphous As40Se60 thin films for optical applications

Progress in Natural Science:Materials International 2014年第3期24卷 239-246页

作者： rashmi chauhan Arvind Tripathi Krishna Kant Srivastava Department of Physic DAV College CSJM University Research Foundation for Education and Technology Department of Physics DBS College CSJM University

The treatment of 100 MeV Ag swift-heavy ion(SHI) irradiation with five different fluences(3 1010, 1 1011, 3 1011, 1 1012, and3 1012ions/cm2) was used to design optical and structural properties of amorphous(a-) As40Se60 chalcogenide thin films. Swanepoel method was applied on transmission measurements to determine the changes in optical bandgap, Tauc parameter and linear optical parameters, i.e., linear optical absorption, extinction coefficient and linear refractive index. Dispersion of the material was determined by Wemple–DiDomenico *** in nonlinear optical parameters of third-order optical susceptibility and nonlinear refractive index were determined using semi-empirical relations. Changes in surface morphology of the films were investigated using SEM observation, which indicated that fluence 3 1012ions/cm2was upper threshold limit for these films for ion treatment. It is observed that optical bandgap reduces from 1.76 eV to 1.64 eV, and nonlinear refractive index increases from 1.31 10 10[esu] to 1.74 10 10[esu]. Linear refractive index initially increases from 2.80 to 3.52(for fluence3 1010ions/cm2) and then keeps decreasing. The observed changes in optical properties upon irradiation were explained in terms of structural rearrangements by Raman measurement. The study was compiled with the previous literature to propose SHI as an effective optical engineering technique to achieve desired changes according to the need of optical/photonic applications.

关键词： Amorphous chalcogenide thin films Ion irradiation Linear and nonlinear optical properties Swanepoel method Semi-empirical relations Raman measurements

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Linear and nonlinear optical changes in amorphous As2Se3 thin film upon UV exposure

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Progress in Natural Science:Materials International 2011年第3期21卷 205-210页

作者： rashmi chauhan Amit Kumar SRIVASTAVA Arvind TRIPATHI Krishna Kant SRIVASTAVA Department of Physic DAV CollegeCSJM UniversityKanpur208001India Department of Physics DBS CollegeCSJM UniversityKanpur208006India Materials Science Programme 4. Research Foundation for Education and Technology 5. Department of Physics DBS CollegeCSJM University

Amorphous As2Se3chalcogenide thin film was exposed to UV light(i line and g line) using mercury lamp for 30 min. XRD,UV/VIS spectroscopy and thickness measurements were taken for unexposed and exposed thin film for structural and optical *** optical constants(linear refractive index,extinction coefficient and linear optical absorption coefficient) of the film were calculated from transmission spectra using Swanepoel *** bandgap was determined using Tauc’s relation of indirect bandgap *** of the material was described by single-oscillator Wemple-DeDiDomenico model. Nonlinear optical constants(χ~((3)) and n2) were determined from linear optical parameters using semi-empirical relations in long wavelength *** changes in linear optical parameters(increase in refractive index,and extinction coefficient;reduction in optical bandgap),nonlinear optical parameter(increase inχ~((3))) are proposed for various photonic applications.

关键词： amorphous chalcogenide thin films UV exposure optical properties swanepoel method Wemple-DeDiDomenico model semi-empirical relations

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Photo-induced optical changes in GexAs40Se60-x thin films

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Progress in Natural Science:Materials International 2010年第1期20卷 54-60页

作者： rashmi chauhan Amit Kumar SRIVASTAVA Arvind TRIPATHI Krishna Kant SRIVASTAVA Department of Physic DAV College Kanpur 208001India Material Science Programme ⅡT Kanpur 208016 India Epsilonium Systems Commercial Complex ChunniganjKanpur 208001India Department of Physics DBS College Kanpur 208006India

Ge-As-Se chalcogenide thin films show a wide range of photosensitivity,which is utilized for the fabrication of micro-optical elements for integrated *** photosensitivity of GexAs40Se60-x（x=0,15）chalcogenide thin films for UV light was *** that purpose,the bulk samples of GexAs40Se60-x（x=0,15）chalcogenide glasses were prepared using conventional melt quenching technique,and thin films were prepared using thermal evaporation *** thin films were exposed to UV light for two *** natures of bulk samples and thin films were verified by XRD and chemical compositions were verified by EDX *** thicknesses of the thin films were measured using a thickness *** optical analysis of these thin films was done using transmission spectra in wavelength range of 300-900 *** bandgap was determined by first peak of transmission derivative as well as extrapolation of Tauc's plot.R2analysis was done using R software to ensure that the material is indirect bandgap *** is observed that two hours UV exposure causes photo-darkening along with photo-expansion in As40Se60thin films,while photo-bleaching and photo-densification for Ge15As40Se45thin ***,the amounts of photo-induced optical changes for Ge15As40Se45thin films are smaller than those for As40Se60thin *** changes in optical absorption,bandgap and thickness are understood based on the bonding rearrangement caused by UV exposure.

关键词： chalcogenide glasses thin films optical properties photo-induced effect optical band gap UV exposure R software

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Optical properties of amorphous thin film of Se-Te-Ag system prepared by using thermal evaporation technique

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Progress in Natural Science:Materials International 2011年第1期21卷 36-39页

作者： Madhu MISHRA rashmi chauhan Anju KATIYAR K.K.SRIVASTAVA Department of Physics Dayanand Braiendra Swarup D.B.S.(P.G.) CollegeKanpur(U.P.)India Department of Physics D.A-V.(P.G.) CollegeKanpur(U.P.)India Department of Physics Dayanand Brajendra Swarup D.B.S.(P.G.) CollegeKanpur(U.P.)India

Optical reflection and transmission spectra of Se80-xTe20Agx(where x=0,5,10 and 15,molar percent) chalcogenide thin films have been obtained in the range 300-1 200 nm at room *** samples are prepared by melt quenching technique and thin films are obtained by using vacuum evaporation technique on glass transition at room *** present paper reports the effect of Ag contents on various optical parameters such as optical band gap,refractive index,extinction coefficient,absorption *** spectra are used for calculating these optical *** band gap Egis determined from the plot of (ahv)1/2versus *** and imaginary parts of the dielectric constant changes slightly with the variation of Ag contents in different *** film exhibits indirect band gap which increases with increasing Ag *** observed behavior is explained on the basis of Davis and Mott model for the density of *** absorption coefficient of thin films exhibits linear dependence on photon *** optical parameters are calculated by using theory of *** the optical parameters change with the variation of the film *** spectrophotometer JASCO-UV/VIS/NIR is used to determine optical constants.

关键词： chalcogenide thin film band gap optical constant

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Magnification:The game changer in dentistry

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World Journal of Methodology 2025年第2期15卷 74-82页

作者： Sachin chauhan Radha chauhan Prashant Bhasin Meenu Bhasin Department of Conservative Dentistry and Endodontics Sudha Rustagi College of Dental Sciences and ResearchFaridabad 121002India Department of Prosthodontics and Crown and Bridge and Oral Implantology Mahatma Gandhi Dental College and HospitalJaipur 302022India Department of Periodontics Sudha Rustagi College of Dental Sciences and ResearchFaridabad 121002India

During dental examinations and treatments,many dentists are using magni-fication to improve their *** dental operating microscope serves as the most effective tool for this purpose,enhancing the quality,longevity,and outcome of clinical *** review will explore the latest research and data on the importance of magnification devices in dentistry,including diagnostic methods,treatment options and ergonomics in specialities such as restorative dentistry,endodontics,pedodontics,periodontics,and *** review aims to provide insights into the optimal magnification for different clinical situations,the specific benefits of dental operating microscopes for each dental branch,and their limitations.

关键词： Magnification Vision Endodontics Dentistry Dental operating microscope

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Present status and future directions:Apexification

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World Journal of Methodology 2025年第1期15卷 26-32页

作者： Sachin chauhan Radha chauhan Prashant Bhasin Bhavna G Sharaf Department of Conservative Dentistry and Endodontics Sudha Rustagi College of Dental Sciences and ResearchFaridabad 121002HaryanaIndia Department of Prosthodontics and Crown and Bridge and Oral Implantology Mahatma Gandhi Dental College&HospitalJaipur 302022RajasthanIndia Department of Pedodontics and Preventive Dentistry Sudha Rustagi College of Dental Sciences and ResearchFaridabad 121002HaryanaIndia

The success rate of apexification is primarily determined by multiple factors,including the material used,the size of the open apex compared to the length of the root,and the technique used in each *** main objective of this review was to provide an update on the present management of open apex to identify factors and circumstances that may influence the success of apexification using different materials and *** research on apexification should focus on how to treat open apices with wide periapical lesions without ***,the predictability of these parameters with non-surgical procedures was uncertain,but now,with the use of a dental operating microscope,it has become more *** reason could be that extra visits are no longer required due to major advances in the armamentarium and materials used for apexification.

关键词： Bioceramics Magnification Biodentine Mineral trioxide aggregate Apexification Open apex

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A comprehensive investigation on nonlinear vibration and bending characteristics of bio-inspired helicoidal laminated composite structures

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Applied Mathematics and Mechanics(English Edition) 2025年第1期46卷 81-100页

作者： S.SAURABH R.KIRAN D.SINGH R.VAISH V.S.chauhan School of Mechanical and Materials Engineering Indian Institute of Technology Mandi

Bio-inspired helicoidal composite laminates, inspired by the intricate helical structures found in nature, present a promising frontier for enhancing the mechanical properties of structural designs. Hence, this study provides a comprehensive investigation into the nonlinear free vibration and nonlinear bending behavior of bio-inspired composite plates. The inverse hyperbolic shear deformation theory(IHSDT) of plates is employed to characterize the displacement field, with the incorporation of Green-Lagrange nonlinearity. The problem is modeled using the C0finite element method(FEM), and an in-house code is developed in the MATLAB environment to solve it numerically. Various helicoidal layup configurations including helicoidal recursive(HR), helicoidal exponential(HE), helicoidal semi-circular(HS), linear helicoidal(LH), and Fibonacci helicoidal(FH)with different layup sequences and quasi-isotropic configurations are studied. The model is validated, and parametric studies are conducted. These studies investigate the effects of layup configurations, side-to-thickness ratio, modulus ratios, boundary conditions, and loading conditions at different load amplitudes on the nonlinear vibration and nonlinear bending behaviors of bio-inspired composite plates. The results show that the laminate sequence exerts a substantial impact on both nonlinear natural frequencies and nonlinear bending behaviors. Moreover, this influence varies across different side-to-thickness ratios and boundary conditions of the bio-inspired composite plate.

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Identification of SNP and InDel variations in the promoter and 5′ untranslated regions of γ-tocopherol methyl transferase(ZmVTE4) affecting higher accumulation of α-tocopherol in maize kernel

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The Crop Journal 2019年第4期7卷 469-479页

作者： Abhijit Kumar Das rashmi Chhabra Vignesh Muthusamy Hema Singh chauhan Rajkumar Uttamrao Zunjare Firoz Hossain The Indian Council of Agricultural Research (ICAR)-Indian Agricultural Research Institute (IARI) New Delhi 110012 India

Deficiency of vitamin-E or tocopherol causes neurological and cardiovascular disorders in humans. Though maize kernel is rich in total tocopherol, the level of α-tocopherol possessing the highest vitamin-E activity is low. Mutant allele of ZmVTE4 with deletion of 7 bp and 118 bp (0/0: most favorable haplotype) in 5′UTR and promoter region, respectively significantly enhances α-tocopherol in maize kernel than wild type haplotype (7/118).α- tocopherol estimation in 15 diverse inbreds revealed that mean α-/γ-tocopherol and α-/ total-tocopherol was much higher in genotypes with favorable haplotype (1.51 and 0.41) than unfavorable class (0.19 and 0.13), respectively. However even within favorable class,α- tocopherol ranged from 4.76 to 30.07 μg g 1. Sequence analysis of part of 5′UTR and promoter of ZmVTE4 among the genotypes with favorable haplotype revealed 14 SNPs (SNP1 to SNP14) and eight InDels (InDel1 to InDel8). SNP7 at 606 bp (G to A), and InDels viz., InDel1 (27 bp), InDel4 (27 bp) and InDel8 (14 bp) differentiated low and high α-tocopherol accumulating inbreds with favorable haplotype. Hence the newly identified SNP and InDels in addition to the already reported InDels can be useful in selection of favorable genotypes with higher α-tocopherol in maize.

关键词： Maize Vitamin-E InDel SNP Biofortification

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Preparation, characterization and luminescence behavior of some samarium complexes

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Rare Metals 2021年第9期40卷 2618-2626页

作者： Archana chauhan Ritu Langyan Department of Chemistry Kurukshetra UniversityKurukshetra 136119India

The synthesis of luminescent complexes of Sm(III) with the general formula [Sm(L)_(3)·(X)] was done in powder form. In the formula, L is 6-methyl-4-oxo-4 H-1-benzopyran-3-carboxaldehyde and X represents 2H_(2)O(C1), 1,10-phenanthroline(C2), 2,20-bipyridine(C3);bathophenanthroline(C4) and neocuproine(C5). The complexes were characterized by using various analytical and spectroscopic tools like elemental analysis, electrospray ionization mass spectrometry(ESI–MS+), Fourier transform infrared spectroscopy(FTIR), ultraviolet–visible(UV–Vis) spectroscopy, thermo-gravimetric analysis/differential thermal gravimetric analysis(TGA/DTG), field emission scanning electron microscopy(FESEM), powder X-ray diffraction(XRD), and photoluminescence(PL)studies. TGA/DTG showed high thermal stability of synthesized complexes. Powder XRD depicts that the average particle size lies in the nano-range. On monitoring at the excitation wavelength of 370 nm, the complexes display characteristic luminescence peaks of Sm(III) at ~564,~600 and ~647 nm assigned to^(4)G_(5/2)→^(6)H_(5/2),^(4)G_(5/2)→^(6)H_(7/2), and ^(4)G_(5/2)→6H9/2 transitions, respectively, with the most intense transition at ~600(orange emission) and~647 nm(bright red emission) in liquid and powder state, respectively. The investigations demonstrate that the synthesized novel complexes might be practically useful in electroluminescent devices, bio-assays, and liquid lasers due to their attractive photoluminescent properties.

关键词： Samarium complexes Luminescence Thermal analysis Quantum yield

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Functionalization of alumina particles to improve the performance of eco-friendly brake-pads

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Friction 2021年第5期9卷 1213-1226页

作者： Vanvirsinh chauhan Jayashree BIJWE Ashish DARPE Centre for Automotive Research and Tribology(formerly ITMMEC) Indian Institute of Technology DelhiHauz-KhasNew Delhi-110016India Mechanical Engineering Department Indian Institute of Technology DelhiHauz-KhasNew Delhi-110016India

Abrasives,such as oxides of alumina(Al),silica(Si),zirconia(Zr),chromium(Cr)etc.,are added to raise the friction level and also to remove the glaze on the disc so that surface will be rejuvenated continuously during braking and will contribute to maintain the desired friction ***,these inorganic particles have less adhesion with the resin/binder and hence are easily dug out during wearing process contributing to higher *** efforts are made to enhance the filler‐matrix adhesion,not only the wear of friction material(FM)should reduce,the particles may stay for a longer time on the tribo‐surface of the pads to contribute fully towards controlling the coefficient of friction(μ).In the present study,alumina particles were selected for siloxane treatment to improve the filler‐matrix *** types of eco‐friendly(free from asbestos and Cu)brake‐pads were developed using alumina as a theme ingredient(treated and untreated)keeping all the parent formulation *** additional type of brake‐pads without alumina particles was also developed to observe the effect of abrasive particles on the tribo‐*** performance properties(physical,mechanical,and tribological)of brake‐pads were compared when evaluated in identical *** tribotesting was done on full‐scale brake inertia dynamometer following the procedure in Japanese automobile standard(JASO C 406).It was observed that siloxane treatment affected both friction and wear of brake‐pads in a beneficial *** resistance got increased 35%for siloxane treated *** surfaces were analysed using scanning electron microscopy(SEM)and energy dispersive X‐ray(EDAX)technique.

关键词： friction materials brake‐pads siloxane treatment friction modifiers inertia brake‐dynamometer

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